Combination filter systems for filtering air streaming into the passenger cabin of a vehicle are known. Such filter systems typically comprise a particulate filter media with a sorbent filter media.
For example, WO-A-95/26802 discloses a combination filter system which comprises a pleated electret charged fiber/nonwoven filter media and an active carbon particle pad. Although the active carbon particle pad exhibits good gas efficiency and/or gas capacity depending on the thickness and carbon content of the pad, the application of such an active carbon particle pad causes a high pressure drop. A high pressure drop is undesirable for vehicle cabin filter systems.
EP-A-383236 discloses an adsorber particle layer that is co-pleated with an electret charged fiber non-woven layer. Although such a combination filter has an acceptable pressure drop, the lifetime thereof is limited, i.e. the filter needs to be replaced frequently.
It is therefore desirable to further improve combination filters, in particular to increase the lifetime of such a filter without raising the pressure drop of such filter to an unacceptable level. Also, for use in motor vehicles, the filter should preferably be designed to meet safety regulations existing in the automotive industry. Further, the combination filter should preferably have the same or improved filter performance. It is furthermore preferred that the combination filter can be produced in a cost effective and easy way and can be easily and effectively installed in a motor vehicle for the purpose of filtering gaseous fluids entering the passenger cabin of such motor vehicle.